Parallel feed antenna system with phase shift switching



April 25, 1967 J, BLASS 3,316,553

PARALLEL FEED ANTENNA SYSTEM WITH PHASE SHIFT SWITCHING Filed OC.. 15, 1962 4 Sheets-Sheet 1 BY new EMe, 45.57, gara/g .Sbf/r April 25, 1967 J. BLAss 3,316,553

PARALLEL FEED ANTENNA SYSTEM WITH PHASE SHIFT SWITCHING Hwa/.w g. Q@ L ETE- 3.

April 25, 1967 J. BLAS?, 3,316,553

PARALLEL FEED ANTENNA SYSTEM WITH PHASE SHIFT SWITCHING Filed 001;. 15, 1962 4 Sheets-Sheet 5 J7 6/ J5 l Z\ f3 fr :51.5. ff a? ...E- 5. Jy

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April 25, 1967 J. BLAss 3,316,553

Filed Oct. 15. 1962 4 Sheets-Sheet 4 JUDD 62,466'

nited States Patent O v 3,316,553 PARALLEL FEED ANTENNA SYSTEM WITH PHASE SHIFT SWITCHING Judd Blass, Bayside, N.Y., assignor to Blass Antenna Electronics Corporation, Long Island City, N.Y., a corporation of Delaware Filed Oct. 15, 1962, Ser. No. 230,358 19 Claims. (Cl. 343-854) This invention relates to antenna systems, and more particularly to directive antennas comprised of a plurality of interrelated radiating elements which may be rapidly switched in a novel and preferable manner to cause the axis of directivity to scan through a sector in space.

Directive antenna systems used for narrow beam operation, such as conventional radar systems, generally must include a means for positioning a narrow beam of energy about a much wider scan angle. One method to scan the beam of such an antenna system is to provide rotation of the reector mount structure or feed. However, because of system inertia and other mechanical difliculties encountered, such prior art systems have been severely limited as to scanning rates and accuracy.

Another method of scanning a beam, and that to which the device of the present invention is directed, is to utilize a line source of energy which is capable of having a uniform phase variation along its length. In such systems, if the phase progressively differs across the linear array, the energy maximum does not occur in the broadside direction, but rather at some angle with respect thereto. Thus, the direction of major response of the antenna can be swept across a sector of space by proper variation of the phase along the array. One way in which such a phase variation has been previously obtained is by the relative movement of the feed source members. One arrangement is to utilize a rotating or oscillating prism intermediate the line source and radiators. Another arrangement is to mechanically vary the path length along a line source beam as employed in the well-known Foster scanner (shown in U.S. Patent No. 2,832,936). Another type of line source scanning system varies the phase between slots along a waveguide or coaxial line by reciprocating motion of the waveguide walls, or rotation of a specially constructed inner coax conductor. Besides exhibiting the aforementioned mechanical ditiiculties, such previously practiced systems have demonstrated high mismatch, loss in gain, and limitation as to possible scan angles.

A further system of the prior art includes a phased array of individual radiating elements each separately fed by a separate transmission line and signal generator. The energy fed to each of the radiated elements is phase controlled to provide the requisite differential phase shift between adjacent elements. Such systems of the prior art have been quite complex, space consuming and have exhibited limitations as to scan angle rates, switch techniques, and energy loss.

My invention avoids the limitations of the prior art devices by providing a simplified arrangement of parallel fed radiating elements wherein the individual path lengths between the main signal feed and the individual radiators may be switched in an extremely simple manner to point a narrow beam in any -direction within a wide sector. The beam direction may preferably be switched in the order of a few nano-seconds (*9 seconds).

Basically my invention provides a linear array of radiating elements which are electrically `connected to individual, but electrically associated wave channels of a novel phase shift network. The novel phase shift network comprises separate branch signal channels for each of the radiating 3,3l'6,5553 Patented Apr. 25, 1967 elements, all of the branch signal channels being fed from a main signal channel in the manner of a travelling wave array via appropriately constructed directional couplers. The antenna system may be reciprocally operated either for transmission or -recep-tion of a narrow beam of energy. However, the ensuing discussion will be principally concerned with the transmit state with it being understood that analogous conditions prevail for receiver operation. The main channel energy is not coupled -directly to the individual radiating elements, but rather in the backward direction wherein they encounter microwave short circuit switches at the other end of the branch signal channels. The microwave short circuit switches reect the incident energy to the radiating elements wherein the energy is then propagated into space.

The phase of the reflected wave at each radiating element will accordingly -be determined by the path length it travels from the directional coupler to the shortening element and then to the radiating element. Thus, the repositioning of the shorting element along the length of the branch signal channel will accordingly introduce a phase shift adjustment in the wave signal propagated by its associated radiating element.

My invention provides for an improved manner of properly setting the shorting positions of each of the individual branch circuit shorting elements, to provide a progressive phase shift across the linear array, such that the individual waves are correlated into a pencil beam of energy which may be rapidly scanned in accordance with the position of the shorting elements.

As a preferred feature of my invention the short circuit switch positions are formed of individual shorting elements positioned along the length of the branch signal channel. In the illustrative embodiment, these individual shorting elements comprise diodes placed across the branch signal guide walls to be appropriately biased into their conducting or blocking states, the former eiiecting a short circuit condition across the guide. I have observed that four such shorting diodes in each branch signal channel are adequate to obtain a sharply defined and accurately positioned beam. A four diode unit as the adjustable short permits a substantial simplification in the manner in which the individual path lengths are varied to obtain the requisite progressive phase shift for beam scanning. A two-bit flip-Hop circuit may advantageously be employed, with the ilip-iiop outputs iconnected to the shorting diodes to provide the necessary bias potential for switching. Such flip-op circuits ,are commercially available in relatively inexpensive, highly compact and extremely reliable assemblies, to thereby provide trouble-free operation. Also, my switching technique preferably avoids the use of multiple receivers, transmitters or ferrite phase Shifters as typically employed in the phased array systems of the prior art.

As another aspect of my invention the line lengths of the energy distribution network, and the separation between the directional couplers of' adjacent branch signal channels, are arranged such that the reflected energy recouplcd into the main transmission line encounters destructive interference. That is, for all possible scan angles within the antenna system capabilities, the additive effect of such recouplcd energy is cancelled to thereby provide a minimum amount of energy loss.

As a further preferred aspect of my invention, the four position diode switches are digitally controlled by the Hipop outputs to provide an extremely accurate positioning of the antenna beam. That is, in previous systems employing analog control networks the presence of noise or other extraneous signals within the system resulted in an inaccuracy in the beam position, therefore limiting the precision of the antenna for such applications as precision lobing. By properly designing the flip-flop switches of my control system, such extraneous signals will be below the threshold switching level. Thus, they will have no effect on the digital output signal, and therefore will not cause an improper positioning of the scan angle.

As still another preferred aspect of my invention, the switches are physically arranged randomly or on a circle for phase aberration and to distribute the secondary energy in a manner which avoids the formation of appreciable side lobes.

As still a further aspect of my invention, the individual radiating elements may be located remote from the branch signal lines of the phase shift adjust network. The radiating elements may typically be connected to the feed structure by coaxial cables, with it being possible for several of such arrays to be connected to a common feed by means of microwave switches. Further, since the antenna feed network is not in the antenna aperture, its physical configuration may preferably be arranged to be compatible with specific space allocation. Various such configurations are shown in my illustrative embodiments wherein the branch Wave signal channels may be folded, or operate in symmetric pairs for physical compactness and system simplification.

It is thus seen that the basic concept of my invention resides in the feeding of a plurality of individual radiating elements from a network of phase adjustable branch signal channels coupled to a common signal channel, wherein the energy is first backward directed against an adjustable short, and the reflected wave is then directed towards the radiating element. The reflected shorts of the individual branch signal waveguides may be rapidly switched (in the order of nano-seconds) to provide for rapid and accurate scanning of the antenna beam.

It is therefore a primary object of this invention to provide a simplified, rapid and accurate antenna scan system.

A further object of this invention is to provide an antenna scan system comprising a predetermined array of individual radiating elements fed from a phase shift network, wherein the phase associated with each of the individual radiate elements may be switched in the order of nano-seconds.

Another object of this invention is to provide such an antenna scan system wherein the phase shift network is digitally controlled to provide highly precise positioning of the antenna beam.

An additional object of this invention is to provide an antenna scan system comprising a plurality of individual branch signal channels each having a radiating element operatively connected to one end, an adjustable shorting element operatively positioned along its other end, and a directional coupler coupling energy-to its intermediate region to be first directed towards the shorting element and then reflected towards the radiating element.

Still a further object of this invention is to provide such an antenna scan system where the shorting elements may be individually adjusted to modify the phase of the emergent signal such that the scan angle determined by the additive phase effect of the individual radiate element wave signals is variable.

Still another object of this invention is to provide such an antenna scan system where the shorting elements comprise individual shorting diodes controlled by a two-bit digital circuit.

These as well as other -objects of the instant invention will readily become apparent after reading the following plete antenna system constructed in accordance with the preferred teachings of my invention.

FIGURES 4 and 5 are end and enlarged cross-sectional views respectively of a shorting diode array which may be used in conjunction with my invention.

FIGURE 6 is a simplified schematic representation of the operation of an individual diode shorting element.

FIGURE 7 is a perspective View of a compact antenna feed system in accordance with the teachings of my invention having a plurality of inter-related branch signal channels compactly arrayed to be interconnected to a common feed source.

FIGURE 8 is a schematic representation of another branch channel array wherein each shorting diode assembly controls the operation of a pair of symmetrically related branch signal channels.

Referring to the figures and FIGURES l and 2 particularly, antenna system 10 comprises a plurality of individual radiating elements 20 which are typically shown as small horns consistent with the requirements of a particular antenna system. Radiating elements 20 may alternatively be flush mounted dipoles, open end ridge waveguide or any other type of well known elements having the frequency response and capture area capabilities imposed by the particular system requirements. Elements 20 are shown arranged to provide a linear array, wherein the phase of the individual signals associated with each of the elements 20 will be progressively shifted to provide for beam directivity.

As is well known in the art the direction of a beam generated by the linear array of individual elements 20 is determined by the phase correspondence of the individual signals; that is, the scan angle of the antenna beam will be in that direction which corresponds to phase coincidence of the individual radiating elements. Thus, by controlling the phase of the signal associated with each of the elements 20, it is seen that scanning of the beam may be obtained. My invention is accordingly directed to an improved and simplified method of rapidly and accurately controlling the phase of the individual signals to thereby provide scanning of the antenna beam.

The individual radiating elements 20 are connected to corporate feed structure 30 by connecting guides 22, which may typically be coaxial cables or other guide means consistent with the frequency characteristics and physical displacement of the antenna system. Each of the guide means 22 connect to the forward end 32 of individual branch wave signal channels 33-47. The branch signal channels comprise a passive microwave network which can be waveguide, coaxial cable or strip transmission line depending on the system frequency and application. Five such channels are illustratively shown in FIGURE l. for purposes of clarity, with it being understood that the actual number of such branch signal channels and associated radiating elements 20 is determined by the required characteristics 4of the particular antenna system. It is thus seen that the radiating elements 20 are physically independent of the branch signal channels 33-47, which may be arranged in accordance with available space allocation.

In the following discussion the antenna system will be discussed in the transmitting mode. However, the system is equally adaptable to be a receiving antenna with its received signal scan angle similarly controlled by the shorting element phase shift within each of the branch signal channels. Each of the branch signal channels 33-47 is electrically connected to main signal channel 50, such that input energy shown as arrow A is coupled to each of the branch signal channels in the manner of a travelling wave arr-ay. A directional coupler 52 interconnects wave signal A into each of the branch signal channels in the backward direction, such that the energy coupled thereto is first directed towards the opposite or rear end 31 of each of the branch signal channels. End 31 includes -a reflective short 55 which then reflects the energy back in the direction of end 32. The reflected wave signal energy will therefore have a phase at end 32 dependent on the length of the path traversed within each of the backward wave channels. It is thus seen that the repositioning of the reflecting short 55 at end 31 will vary the length of this path, and accordingly the phase of the wave at end 32. As will be more fully discussed below, the position of the shorting elements 55 of each of the branch signal channels 33-47 is programmed by beam director unit 80 such that the additive phase effect of the wave signals emergent at end 32, and coupled to radiating elements 20, provides the desired directivity of the scanning beam.

AReference is now made to FIGURE 2 which illustrates the operation of the phase shift adjust of each of the branch signal channels. Input wave signal A in main guide 50 is illustratively shown as travelling into the plane of the paper. At the intersection of main wave signal channel 50 and each of the branch signal channels such as 33, directional coupler 55 is provided, to direct a predetermined portion of the energy of wave signal channel A into the branch signal channel and in the direction towards end 31, as shown by arrows B. End 31 includes an adjustable reflective short 55 which is preferably shown as a longitudinally positioned array of individual diode elements 56. It is to be noted that these short circuits need not be diodes nor be discrete. Alternatively, these elements may be any other device well known in the art to provide an adjustable refiected surface, such as a sliding metal shorting plunger. However, the diode arrangement shown preferably permits a switching arrangement in a more simplified and rapid manner than has heretofore been available, permitting optimum electronic performance. Four such diode elements 56 are shown which may be appropriately switched between their conducting and blocking states to selectively position the short within each of the branch circuits. Incident energy B upon reaching the shorted diode, illustratively shown as 56-3, is reflected and is directed back towards end 32, as shown by arrows C (shown dotted for purposes of clarity). Directional coupler 52 is so designed that very little of the wave energy C will be recoupled back into the main guide 50. Wave energy C will then emerge from end 32 of the branch signal wave guide wherein it is appropriately coupled to radiating element 20. It is thus seen that the phase of the signal C emergent at end 32 may be adjusted by repositioning the shorting means 55. Inasmuch as the signal within the branch signal channel traverses in and up and b'ack direction towards short 55, each of the diode elements 56 are separated by 1/8 of a wavelength at the mean operating frequency of the antennasystem, to provide a 1A wavelength overall path differential to the branch waveguide signal.

Reference is now made to FIGURE 3, which shows in schematic form the operation of the antenna system. Those components previously discussed in conjunction with FIGURES 1 and 2 are indicated by like numerals. Fifteen branch signal channels, numbered 33, 34, 35 47, are typically shown connected as by directional couplers 52 to main signal channel 50 in the manner of a travelling wave array. The successive variation in length of adjacent branch signal channels is provided to correct for delays in the main signal channel 50. Further, the electrical spacing between the successive branch signal channels is appropriately arranged such that the additive effect of the energy D recoupled into main signal channel 50 after reflection by the short 55 will be in destructive interference over all scan angles, thereby providing minimum energy loss. The portion of the recoupled energy which is not destructively interferred may be dissipated by small dummy load 60 at the output end of main guide 50.

The appropriate diodes 56 of the shorting switches 55 are switched into their blocking and conducting states by bias voltages supplied by switching circuits 70. Switching circuits 70 are preferably two-bit ip-op circuits 6 appropriately designed for the speed of operation and reliability of the particular Iantenna system. Preferably, flip-flop circuitry 70 may be solid state circuits disposed within the wave signal guides themselves of each of the branch signal channels. The control signal for flip-flop 70 is generated by beam director unit 80 which drives scan control generator 82, which may typically be a cosine generator having an output signal related to the cosine of the required scan angle. The output signal of scan control generator 82 is presented to scan control network 84 which may typically be an RF delay line network having properly delayed output signals corresponding to the phase shift required of each of the individual branch signal waves to cumul-atively yield the desired scan angle.

The output signals of the scan control network presented to flip-op controls 70 will provide a two-bit digital output coupled to individual shorting elements 56 to thereby establish the differential path lengths for the necessary phase shift of each of the branch channel signals. In a typical case, the input si-gnals presented to each of the microwave control circuits 70 by the scan control network -84 do not correspond to exact multiples of the quarter wave delay obtainable by the four position shorting switch. Thus, where an intermediate amplitude signal is presented to .a switch 70, the phase shift of its associated branch circuit might not be exactly equal to that theoretically required for the desired scan angle. However, should `a sufficient number of branch channels be provided in .the complete antenna system, the cumulative effect of these slight deviations tend to cancel, thereby giving a scan .angle accurately related to the signal generated by beam director unit t8() and scan control generator 82.

It has been found that the digital control of the phase shift obtained in each of the branch channels reduces the susceptibility of the antenna system to errors caused by the generation of noise or other extraneous signals within the circuitry. That is, the circuitry can be designed such that the digital switching -amplitude is kept substantially above any such extraneous signals. Therefore the presence of these signals will not have -an effect on the output count of flip-flop 70 .and hence the phase shift of the individual branch circuits. This permits extreme accuracy in the beam position and affords my invention particular utility for high precision, high frequency lobing.

As a further preferable feature of the invention of the switching diodes 56 of the branch signal channels are physically arranged randomly or on .a circle for phase aberration to thereby prevent the formation of appreciable secondary lobes. Thus, the system can be designed .to concentrate the energy in a narrow beam of energy.

FIGURES 6 and 7 illustrate a preferred configuration -and schematic representation of the diode shorting elements 56. All of the elements 56 of a shorting switch array 55 are disposed within a longitudinal dielectric tube 5-3 to facilitate insertion and removal of the switching arr-ay -as .a unit. The waveguide walls 58 are at ground potential. The anode terminal 57 of diode element 52 is shown connected .to one of the wall surfaces via metall-ic insert 61 in the dielectric tube. The cathode terminal 59 of the diode is connected to a positive DC. bias, which may typically be one of .the outputs of the flip-flop control 70. The DfC. bias presented by the ip-flop output to the cathode S9 is of a sufiicient magnitude to place the diode in lits blocking state, thereby providing an open circuit. Removal of the D.C. bias places diode `56 in its conducting state, thereby providing -a reflective short to the incident microwave signal. Capacitive element 62 is provided for RF bypass of the bias return 63. It is thus seen that the individual diodes 56 .are conveniently contained within a compact unitary structure which may be easily inserted and properly positioned within the end region 31 of the individu-al branch wave channels.

Many configurations of the branch signal network may be practiced within the general teachings of my invention, with one such compact configuration being shown in FIGURE 7. The phase adjust corporate feed network is comprised of two sections 100 and 200 respectively, having main wave signal input channels `150 and 250 connected by a T section 1-10 to common input 120. The branch signal channels of each section occur in paired `decks such as 13S-a, '13S-b, 23S-b and 23S-a respectively. Each of the individual branch signal channels of the individual decks -are coupled to their respective main signal channel in the same manner as shown in conjunction with the discussion of FIGURES l-3. However, the coupling occurs in pairs along the length of the main signal channels y150, 250. That is, wave signal channel 150 contains directional coupler pairs (not shown) coupling into successive pairs of branch signal channels such as 133a, 133b; 134a, 1-34b; 135a, 13511 It is thus seen that compactness and overall simplification of the excitation circuit is provided by having -a single input channel (,120) coupling to two separate channels (-150, 250), which in turn couple to a pair of branch signal channels (100a, 110011, 20001, 200b). The radiating elements 20` coupled to the outputs of each of the branch signal channels may typically be linearly arrayed in the following order: 133a, 13311; 13411, 1341); 135a, 13511; 14511, 145b; 245b, 245e: 234b, 23M; 233b, 233e, to provide a symmetric array of radiating elements fed by a compact arrangement of the phase shift adjust corporate feed network.

FIGURE y8 schematically shows another form of the control switch 70 and corporate feed 10 arrangement whereby there are half as many outputs in the control as antenna elements in the array, with each output controlling two radiating elements symmetrically disposed about the center of the array. The arr-ay is fed by main signal channels 3:50a, 350b, coupled to a common input 320. The shorted ends of symmetrically related branch signal channels (such as 333a, 3-33b) are joined by' a common shorting circuit 355 controlled by a single fliptiop circuit as previously discussed. By appropriate .symmetrical placement of the radiating elements associated with each of the branch signal channels, the phase differential introduced by the respective shortening and lengthening of each of the pair of branch channels suchas 33'3a, 333b provides the aforedescribed scan positioning of the antenna beam.

[It is thus seen that I have provided a novel antenna system whereby the antenna beam may be appropriately shaped and directed by a switched arr-ay of variable phase shift signal channels. The system is constructed .to p rovide extremely rapid scanning and accurate positioning of the antenna beam by the generation of a simple digital signal presented to high speed diode switches..

Appropriate diodes and flip-flop control circuits are presently -available to permit my antenna system to accurately position a two-degree beam withln a 120 sector in the order of a few nano-seconds. Very broad band coverage is possible without loss of antenna gain, even though the band may be varying over a l2:1 band at a l meg-acycle rate.

Although I have described preferred embodiments of my novel invention, many variations and modifications will now be obvious to those skilled in the art, and I prefer therefore to be limited not by the specific disclosure herein but only by the appended claims.

The embodiments of the invention in which an exclusive privilege or property is claimed are defined as follows:

I. An antenna system comprising a plurality of radiating elements; said radiating elements being positioned in ya predetermined array; a plurality of branch signal channels; connecting means operatively connecting each of said radiating elements to corresponding ones of said branch signal channels at a first end region of said branch signal channels; a main signal channel; directional coupler means CII operatively constructed to couple an introduced signal between said main signal channel and said plurality of branch signal channels; said directional coupler means directing said coupled signal towards a second end region of each of said branch signal channels; said second end regions each including reflecting means constructed to reflect said coupled `portion towards said first end region; said first end regions being an outlet for s'aid coupled signals between said branch signal channels and said radiating elements to form a signal beam; adjustment means individually controlling the characteristic of each of said refiecting means whereby the phase of each of said coupled signals at said first end regions may be individually varied; the scan angle of said signal beam determined by the additive phase effect of said coupled signals.

2. An antenna system comprising a plurality of radiating elements; said radiating elements being positioned in a predetermined array; a plurality of branch signal channels; connecting means operatively connecting each of said radiating elements to corresponding ones of said branch signal channels at a first end region of said branch signal channels; a main signal channel; directional coupler means operatively constructed to couple an introduced signal between said main signal channel and said plurality of branch signal channels; said directional coupler means directing said coupled signal towards a second end region of said branch signal channel; said second end t region including reflecting means constructed to reflect said coupled portion towards said first end region; said first end regions being an outlet for said coupled signals between said branch signal channels and said radiating elements to form 'a signal beam; adjustment means individually controlling the characteristic of each of said reflecting means whereby the phase of each of said coupled signals at said first end regions may be individually varied; the scan yangle of said signal beam determined by the additive phase effect of said coupled signals; said refiecting means including shorting means; said adjustment means selectively positioning said shorting means along the second end region of said branch signal channel.

3. The antenna system of claim 2 wherein said shorting means include a plurality of individual shorting elements along the length of said branch signal channel.

t 4. The antenna system of claim 3 wherein said shorting elements comprise diodes placed across said branch signal channel.

5. The antenna system of claim 3 wherein said adjustment means presents a digital signal to s'aid shorting elements, said digital signal controlling the operating state of said shorting elements.

6. The antenna system of claim 4 wherein said adjustment means presents a biasing signal to selected ones of said diodes; said biasing signal switching said diodes between their conducting and blocking states.

7. An antenna system comprising a plurality of radiatlng elements; said radiating elements being positioned in a predetermined array; a plurality of branch signal channels; connecting means operatively connecting each of said radiating elements to corresponding ones of said branch signal channels at a first end region of said branch signal channels; a main signal channel; directional coupler means operatively constructed to couple an introduced signal between said main signal channel and s'aid plurality of branch signal channels; said directional coupler means directing said coupled signal towards a second end region of said branch signal channel; said second end region including reflecting means constructed to reflect said icou- -pled portion towards said first end region; said first end regions being an outlet for s'aid coupled signals between said branch signal channels and said radiating elements to form a signal beam; adjustment means individually controlling the characteristic of each of said reflecting means whereby the phase of each of said coupled signals at said first end regions may be individually varied; the scan angle of said signal beam determined by the additive phase eiect of said coupled signals; said reflecting means comprising a group of diodes positioned along the second end region of said br'anch signal channel; each of said diodes having a conducting and a blocking state; said diodes when in said conducting state providing a reective short to said coupled energy; said adjustment means presenting a biasing signal to said diode elements whereby switching said diode elements between said conducting and said blocking states.

8. The antenna system of claim 7 wherein said biasing signal is a digital circuit signal.

9. The 'antenna system of claim 7 wherein each of said branch channels include four of said diode elements; said adjustment means being a two-bit digital circuit; the output signals of said digital circuits providing the switching bias of said diode elements.

10. The antenna system of claim 9 further including a scan control means; said scan control means presenting sequentially related digital control signals 4to said two-bit digital circuits; whereby said diode elements are selectively adjusted to control the scan angle of said signal beam.

11. The antenna scan system of claim 1 wherein adjacent ones of said directional coupler means being operatively positioned along said main coupling channel to effect destructive interference of portions of said coupled signal which are recoupled from said branch signals back into said main signal channel.

12. The antenna system of claim 1 wherein said radiating elements are positioned remote from said branch signal channels.

13. An antenna system comprising a plurality of radiating elements; said radiating elements being positioned in a predetermined array; a first and second plurality of branch signal channels; connecting means operatively connecting each of said radiating elements to corresponding ones of said branch signal channels at a first end region of said branch signal channels; a main signal channel; directional coupler means operatively constructed to couple an introduced signal between said main signal channel and said plurality of branch signal channels; said directional coupler means directing said coupled signal towards a second end region of said branch signal channel; said second end region including reflecting means constructed to reflect said coupled portion towards said first end region; said first end regions being an outlet for said coupled signals between said branch signal channels and said radiating ele-ment to form a signal beam; adjustment means individually controlling the characteristics of each of said reflecting means, whereby the phase of each of said coupled signals at said first end regions may be individually varied; the scan angle of said signal beam determined by the additive phase effect of said coupled signals, said main signal channel intersecting each of said branch signal channels intermediate said first and second end regions thereof; said directional coupler means comprising an individual directional coupler at the intersecting region of said main signal channel and each of said branch signal channels.

14. An antenna system comprising a plurality of radiating elements; said radiating elements being positioned in a predetermined array; a first and second plurality of branch signal channels; connecting means .operatively connecting each of said radiating elements to corresponding ones of said branch signal channels at a first end region of said branch signal channels; a main signal channel; directional coupler means operatively constructed to couple an introduced signal between said main signal channel and said plurality of branch signal channels; said directional coupler means directing said coupled signal towards a second end region of said branch signal channel; said second end region including reflecting means constructed to reflect said coupled portion towards said first end region; said first end regions being an outlet for said coupled signals between said branch signal channels and said radiating element to form a signal beam; ad-

justment means individually controlling the characteristics of each of said reflecting means, whereby the phase of each of said coupled signals at said first end regions may be individually varied; the scan angle of said signal beam determined by the additive phase effect of said coupled signals, said main signal channel intersecting each of said branch signal channels intermediate said first and second end regions thereof; said directional coupler means comprising an individual directional coupler at the intersecting region of said main signal channel and each of said branch signal channels; said first and second plurality of branch signal channels positioned along opposite surfaces of said main signal channel in a sandwiched-like arrangement; the radiating elements of adjacent ones of said first and second plurality of branch signal channels being alternately arranged in a linear array.

15. An antenna system comprising a plurality 'of radiating elements; said radiating elements being positioned in a predetermined array; a first and second plurality of branch signal channels; connecting means operatively connecting each of said radiating elements to corresponding ones of said branchsignal channels at a first end region of said branch signal channels; a main signal channel; directional coupler means operatively constructed to couple an introduced signal between said main signal channel and said plurality of branch signal channels; said directional coupler means directing said coupled signal towards a second end region of said branch signal channel; said second end region including reecting means constructed to reflect said coupled portion towards said first end region; said first end 4regions being an outlet for said coupled signals between said branch signal channels and said radiating element to form a signal beam; adjustment means individually controlling the characteristics of each of said reflecting means, whereby the phase of each of said coupled signals at said first end regions may be individually varied; the scan angle of said signal beam determined by the additive phase effect of said coupled signals, said main signal channel intersecting each of said branch signal channels intermediate said first and second end regions thereof; said coupling means comprising an individual directional coupler at the intersecting region of said main signal channel and each of said branch signal channels; said reflecting means comprising a group of diodes positioned along the second end region of said branch signal channel; each of said diodes having a conducting and a blocking state; said diodes when in said conducting state providing a reflective short to said coupled energy; said adjustment means presenting a biasing signal to said diode elements thereby switching said diode elements between said conducting and said blocking states; the second end regions of corresponding ones of said first and second plurality of branch signal channels operatively connected for form pairs; a single group of diodes being positioned in the intermediate connecting region of each of said pairs, whereby a single diode group controls the phase of a pair of branch signal channels.

16. A scanning antenna system comprising =a plurality of wave signal channels; a plurality of radiating elements, each electrically connected to a first end region of corresponding ones of said wave signal channels; a second end region of said wave signal channels including a signal reflecting means; common excitation means including directional coupler means for presenting a wave signal to each of said wave signal channels; said wave signals traversing a path directed towards said reflecting means and from said reflecting means oppositely directed towards said first end region; adjustment means individually controlling the characteristics of each of said reflecting means whereby the phase of said wave signal at each of said first end regions may be individually varied; the scan angle of said antenna system determined by the additive phase effect of said wave signals at the first end region of said wave channels; said reflecting means including shorting means; said adjustment means selectively positioning said lll shorting means -along the second end region of said Wave signal channel whereby the overall length of said wave signal path is varied.

17. The scanning antenna system of claim 16 wherein said shorting means includes a plurality of electrically controllable shorting elements; said adjustment means presenting a digital control signal to said shorting elements.

18. A scanning antenna system comprising a plurality of wave signal channels; a plurality of radiating elements, each electrically connected to a first end region of corresponding ones of said wave signal channels; a second end region of said wave signal channels including a signal relfleeting means; common excitation means including directional coupler means for presenting a wave signal to each of said wave signal channels; said wave signals traversing a path directed towards said reflecting means and from said reflecting means oppositely directed towards said first end region; adjustment means individually controlling the characteristics of each of said reflecting means whereby the phase of said wave signal at each of said irst end regions may be individually varied; the scan angle of said antenna system determined by the additive phase effect of said wave signals at the first end region of said wave channels; said reecting means comprising a group of diodes 25 positioned along the second end region of said wave signal channel; each of said diodes having a conducting and a blocking state; said diodes when in said conducting state providing a reective short to said wave signal energy; said adjustment means presenting a biasing signal to said diode elements thereby switching said diode elements between said conducting and said blocking states.

19. The scanning antenna system of claim 18 further including a scan control means; said scan control means presenting sequentially related digital control signals to said adjustment means, whereby said diode elements are selectively adjusted to control the scan angle of said signal beam.

References Cited by the Examiner UNITED STATES PATENTS 2,831,190 4/1958 Trinter 343-1006 2,878,472 3/1959 Sterns 343-853 3,133,282 5/1964 Rosen 343-100.6 3,136,950 6/1964 Mackey 333-1.1 3,137,856 6/1964 Tashjian 343-854 3,178,659 4/1965 Smith et al 333-7 3,182,330 5/1965 Blume 343-854 3,202,942 8/1965 Garver et al 307-885 ELI LlEBERMAN, Primary Examiner.

HERMAN KARL SAALBACH, R. F. HUNT,

Assistant Examiners. 

1. AN ANTENNA SYSTEM COMPRISING A PLURALITY OF RADIATING ELEMENTS; SAID RADIATING ELEMENTS BEING POSITIONED IN A PREDETERMINED ARRAY; A PLURALITY OF BRANCH SIGNAL CHANNELS; CONNECTING MEANS OPERATIVELY CONNECTING EACH OF SAID RADIATING ELEMENTS TO CORRESPONDING ONES OF SAID BRANCH SIGNAL CHANNELS AT A FIRST END REGION OF SAID BRANCH SIGNAL CHANNELS; A MAIN SIGNAL CHANNEL; DIRECTIONAL COUPLER MEANS OPERATIVELY CONSTRUCTED TO COUPLE AN INTRODUCED SIGNAL BETWEEN SAID MAIN SIGNAL CHANNEL AND SAID PLURALITY OF BRANCH SIGNAL CHANNELS; SAID DIRECTIONAL COUPLER MEANS DIRECTING SAID COUPLED SIGNAL TOWARDS A SECOND END REGION OF EACH OF SAID BRANCH SIGNAL CHANNELS; SAID SECOND END REGIONS EACH INCLUDING REFLECTING MEANS CONSTRUCTED TO REFLECT SAID COUPLED PORTION TOWARDS SAID FIRST END REGION; SAID FIRST END REGIONS BEING AN OUTLET FOR SAID COUPLED SIGNALS BETWEEN SAID BRANCH SIGNAL CHANNELS AND SAID RADIATING ELEMENTS TO FORM A SIGNAL BEAM; ADJUSTMENT MEANS INDIVIDUALLY CONTROLLING THE CHARACTERISTIC OF EACH OF SAID REFLECTING MEANS WHEREBY THE PHASE OF EACH OF SAID COUPLED SIGNALS AT SAID FIRST END REGIONS MAY BE INDIVIDUALLY VARIED; THE SCAN ANGLE OF SAID SIGNAL BEAM DETERMINED BY THE ADDITIVE PHASE EFFECT OF SAID COUPLED SIGNALS. 